Touch technologies are the latest development in human interface techniques to computational and communication devices. Due to the paradigm changes imposed on the semiconductor technology by Moore's law, improvements in speed and response time of computer systems allow users to interface with computer systems using their fingers.
The keyboard was an early form of user input interface to the computer. It migrated naturally from the typewriter world. The mouse was added to the user interface as another natural and faster way of user input. Noteworthy is that the main driver for this advancement was the development of silicon technology, which allowed a graphical user interface to be supported. Fast movement of the cursor on the screen in response to mouse movement and on-screen selection rather than specification of textual input minimized typing on the keyboard. This represented another paradigm shift to the extent that most computers and notebooks started to use a mouse.
The semiconductor technology has further advanced. Whereas when the mouse was introduced, a graphical user interface became a useful user interface, the technology in screen and graphics hardware and device drivers has advanced another quantum to enable touch technologies. The functions of the keyboard and the mouse are being replaced by a more direct human interface. The keyboard interface is being simulated by touch as well, on the screen. This is attractive as it manifests tremendous power in the user's hand. The computing power for screen manipulation has improved substantially to react to multiple touches for sensing touches (detection), positioning touches (resolution), cognition of touches and responses to touches. These operations are now supportable on hand-held devices at response times conducive to user interaction.
Single touch occurs when a finger or stylus creates a touch on the surface of a touch sensor. It is subsequently detected by a touch controller. The application can determine the coordinates of the touch event. Touch technologies have been integrated into many devices. These devices typically do not have the ability to detect or resolve more than a single touch point at a time. Pens enable the same input characteristics as a finger, but with greater pointer accuracy. Active pens can provide more control and uses for the touch system such as drawing and palm rejection capabilities.
Improvements to firmware, software and hardware by many single touch technologies have increased their touch functionality. Some touch technologies can use advanced processing capabilities to “detect” or recognize that a second touch event is occurring. Unfortunately, single touch systems cannot resolve the exact location of the second touch event. Instead, they rely on processes to interpret the intended gesture event input.
The “two touch” refers to a touch system that can detect and resolve two distinct, simultaneous touch events. Drawing two parallel lines on the screen at the same time is an example of the “two touch.” The multi-touch refers to a touch system's ability to simultaneously detect and resolve a minimum of three or more touch points. All three or more touches are detected and fully resolved. This results in an improved touch experience. Multi-touch is considered to become a widely-used interface. This is due to its efficiency, speed and intuitiveness of the technology. Multi-touch technology enables users to pinch, swipe, rotate, and other actions. These allow for richer and more direct interaction with digital content. For an exemplary application, photographs can be rotated, resized and moved individually and in groups.
The two finger multi touch system has some advantages. Since simultaneous use of two fingers is required, restrictions are placed on the allowable movement of the user. For example, it is very hard to draw a circle with a finger and a thumb or with two fingers. Limitations of the human palm place hard constraints on the user's ability to complete a circle in one pass. This is also true for any close ended figure, that is much easier to draw using one finger. A user's hand usage is heavily biased towards the use of the index finger or the index finger and the thumb. Therefore, improvements to two finger simultaneous touch interfaces are needed.